Perspective | Published:

The pros, cons, and many unknowns of probiotics


Consumption of over-the-counter probiotics for promotion of health and well-being has increased worldwide in recent years. However, although probiotic use has been greatly popularized among the general public, there are conflicting clinical results for many probiotic strains and formulations. Emerging insights from microbiome research enable an assessment of gut colonization by probiotics, strain-level activity, interactions with the indigenous microbiome, safety and impacts on the host, and allow the association of probiotics with physiological effects and potentially useful medical indications. In this Perspective, we highlight key advances, challenges and limitations in striving toward an unbiased interpretation of the large amount of data regarding over-the-counter probiotics, and propose avenues to improve the quality of evidence, transparency, public awareness and regulation of their use.

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We thank the members of the Elinav and Segal laboratories for discussions and apologize to authors whose work was not included due to space constraints. J.S. is the recipient of the Strauss Institute research fellowship. N.Z. is supported by the Gilead Sciences International Research Scholars Program in Liver Disease. E.S. is supported by the Crown Human Genome Center; the Else Kroener Fresenius Foundation; Donald L. Schwarz, Sherman Oaks, CA; Jack N. Halpern, NY, NY; Leesa Steinberg, Canada; and grants funded by the European Research Council and the Israel Science Foundation. E.E. is supported by Y. and R. Ungar, the Abisch Frenkel Foundation for the Promotion of Life Sciences, the Gurwin Family Fund for Scientific Research, the Leona M. and Harry B. Helmsley Charitable Trust, the Crown Endowment Fund for Immunological Research, the estate of J. Gitlitz, the estate of L. Hershkovich, the Benoziyo Endowment Fund for the Advancement of Science, the Adelis Foundation, J. L. and V. Schwartz, A. and G. Markovitz, A. and C. Adelson, the French National Center for Scientific Research (CNRS), D.L. Schwarz, the V.R. Schwartz Research Fellow Chair, L. Steinberg, J. N. Halpern, A. Edelheit, grants funded by the European Research Council, a Marie Curie Integration grant, the German-Israeli Foundation for Scientific Research and Development, the Israel Science Foundation, the Minerva Foundation, the Rising Tide Foundation, the Helmholtz Foundation, and the European Foundation for the Study of Diabetes.

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Correspondence to Eran Segal or Eran Elinav.

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E.S. and E.E. are paid consultants at DayTwo and BiomX. None of their work on microbial therapies is related to, funded or endorsed by, shared or discussed with or licensed to any commercial entity.

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Fig. 1: Precision aspects of probiotics.
Fig. 2: Mechanistic interactions between probiotics and the host and its microbiome.